(Addresses Educational Needs) As residents of a community have different educational needs, and there is a need for a system for electronically delivering audio-visual educational programming from an electronic library to the learners physical location, and it is desirable to deliver educational programming when the learner desires such programming, and it is required that learners have the ability to start, stop, fast-forward and rewind the playing of such programming; apparatus is needed to provide for such requirements. This invention provides for such educational needs.
(A Form of Pay TV) Although an educational electronic library and delivery system may be publically funded by a community library or a public educational institution, the sponsoring agencies may wish to incorporate such a service on a user pay basis. In addition, private educational institutions may desire to make use of such apparatus. When so employed the system becomes a form of pay television.
(Elimination of Monopoly) Presently competing cable TV operators within a franchise area are faced with the uneconomical prospect of duplicate distribution networks. Usually this has resulted in an avoidance of competition, the result being that a single operator monopolizes the distribution of cable TV programming within a franchise area. Potential competing operators are discouraged from entering into competition within a franchise area as the duplicate distribution network has a potential of only 50% of the return of a monopoly franchise area of equal investment cost. It is observed that approximately 15% of the capital investment in a cable TV distribution system is in primary trunking costs compared with 85% in the secondary distribution network. If the secondary distribution network could be made available for use by competing cable TV operators and duplication of same avoided, then the probability of a plurality of cable operators competing for business within an area becomes economically feasible.
(Accessability Limits) An educational electronic library and delivery system requires the ability to provide all residents of an urban society, who have a desire to access and a means to pay for such educational services, the ability to access the widest possible variety of programming at the time desired with the minimum of conflict between users. All pay TV systems employed to date severely restrict user choice as the apparatus provided is limited in its capacity to simultaneously access and deliver the required quantity and variety of programs.
(Prior-Art-Bradley, switching/bus techniques) Most cable TV systems in use today frequency division multiplex a plurality of subscription television channels and a plurality of pay per view channels onto a single coaxial cable for transmission and distribution to residences. A few also allocate some channel capacity for the transmission of user selected video-on-demand programming from a central library to user's residences. An example of such apparatus is given in an associate prior patent, Bradley, Stretten, Stretten and Wentzel (U.S. Pat. No. 4,878,245). The prior Bradley et al. patent teaches that user programming choice can be expanded by using the same radio-frequency TV channels to carry different programming by separating duplicate frequencies onto a plurality of physically separate transmission paths, each path serving a separate group of subscribers, where each user controls a radio frequency isolation switch to permit the user to access extra channels when desired.
In a previous associated patent, Bradley, Stretten, Stretten and Wentzel (U.S. Pat. No. 4,878,245), each community of about 100 homes was provided an individual fiberoptic fiber as the transmission facility from a central electronic library to the community. With this previous proposed arrangement the quantity of programs that could be simultaneously delivered is restricted by the capacity of the fiber link. Also if a single library serves the entire urban centre, many of the communities of 100 homes would be very distant from the library making the cost of adding additional fiberoptic transmission facilities expensive. In addition different communities have different educational and cultural needs. For example, an Italian community would want programming different than a Hispanic community, a low income community would have a greater need for basic job skills programming than a high income community. Therefore, it would be more efficient to store and transmit special interest programming from a library located in the neighborhood community than transmit such programming over a long distance from the central library. This previous proposal suggests no alternative to a single centralized electronic library.
Programming should therefore be classified and distributed among a network of libraries in order to reduce implementation cost and improve transmission efficiencies. Programming for which there is a common interest, and high demand, should be distributed from a central library. Programming of local interest and modest demand should be stored and distributed from libraries located in the neighborhood community. Programming of common interest but very low demand should be distributed from the central library for short term storage at a local library where it is available for user access and control. The apparatus embodied herein improves upon the distribution efficiency by taking into consideration the differing nature of and demand for programming.
(VCR Like Control) In addition our previous embodiment provided user control of only the starting of the delivery of a program. No means is provided for the user to control the stopping, fast forwarding, rewinding, or replaying of a program. As the educational user needs to have access to the ordering and control link at all times to permit control over the delivery of the programming an alternative to the public telephone network, as proposed in our previous patent, was required in order to avoid telephone facility blocking problems.
(Control Path Blocking) Another object of this invention is the provisioning, for each of a plurality of users, an ordering and control link that is effectively available for user at all times, and that is intrinsically secure.
The provisioning of the start/stop, wind/rewind feature is another reason for not locating educational programming at the central library as learners could tie up expensive, long transmission facilities for extended periods of time.
(Prior Art Sub-Centres) Nakajima et al (U.S. Pat. No. 4,538,176) and Yabicki et al (U.S. Pat. No. 4,518,989), proposed an electronic library system with optional sub-centres located between the location of where the video/audio files are stored and the end user. The purpose of sub-centres is to reduce the cost of potentially long transmission lines from the central program file to the end user. Sub-centres do not store files for direct access by users but only have buffer memory capability to permit high speed transmission from the central file and the sub-centre and real-time retransmission to the user. The apparatus as embodied in both patents fails to address the special needs of educational programming services, the savings realized by storing some programs near the physical location of the end user and other programs at a central location, and the congestion problems associated with the use of the public telephone network for control and ordering.
(Security) Most pay TV systems, including the Bradley et al previous embodiment, simultaneously deliver the same programming to a plurality of physical location within the unique fiberoptic fed neighborhood. Our previous embodiment uses a combination of filters and switches to block the delivery of programs to a potential users television receiver should the potential user not wish to pay for the programming. Physical security means are required to prevent unauthorized users from receiving the pay programming by tampering with the filters and switches. Occasional physical inspection is required to deter tampering. Most other pay TV systems use addressable encryption or jamming apparatus to prevent programming, for which a potential user has decided not to pay or is not permitted to purchase, from being intelligently received. The three most common methods of defeating such apparatus are; by transferring the internal unique descrambler identity keys from an authorized unit to an unauthorized unit thus making both units identical as far as addressing signals are concerned, by extracting the decoded descrambling keys from an authorized descrambling device and programming into an unauthorized descrambler; by relocating an authorized descrambler from a physical location where it is permitted to be used to a location where it is not (for example, from a private residence where private viewing is permitted to a public establishment where public viewing is denied).
Each of the above security systems have only a limited lifetime. Some months or years after installation methods of defeating the apparatus become widespread and the system operator is required to change out the security apparatus. Another object of this invention is the proposal of a security method that is intrinsically secure, that does not require the use of encryption or jamming apparatus.
This embodiment improves upon the security method embodied in our previous patent by moving the point of programming denial into a single secure neighborhood building or structure, thus eliminating the need for physical inspection of a plurality of apparatus distributed throughout the neighborhood.
(Bulk Problems) The disadvantage of feeding every user location from a single neighborhood distribution point is that should coaxial cable be used the physical bulk of the cable becomes a burden.
This embodiment improves upon Nakajima and Yabicki by using conventional telephone paired copper wires, or low cost fiber optics as the transmission medium from the neighborhood library to the users physical location. Should the length of the transmission line from the local library to the user's location be less than typically 2 km., then the video and audio signals are transmitted via conventional telephone cable, one pair for the video and one pair for the audio, from the local library to the home. Should the distance be longer or a higher bandwidth be required (for the simultaneous transmission of 2 to 4 Amplitude Modulated Vestigial Sideband (AM VSB) RF channels), then this embodiment proposes the use of a low cost optical transmission line consisting of a low cost optical energy source, and a relatively low bandwidth, high loss fiber. By using paired telephone cable or optical transmission, as opposed to coaxial cable transmission, the physical bulk of the cabling can be reduced as both are small compared with that of conventional coaxial cable transmission systems.
Nakajima and Yabicki, indicates the use of electrical transmission methods. They require no encryption or jamming apparatus but either they must utilize a greater number of subcentres which expands their physical security needs, or cable bulk becomes a problem; a problem that they have failed to address.
(Prior Art Problems-security/blocking) Typical examples of user controlled video-on-demand pay TV system are that outlined by Monslow et al. (U.S. Pat. No. 4,890,320) and Abraham (U.S. Pat. No. 4,590,516; 4,567,512; and 4,521,860). Both the Maslow and Abraham apparatus combine a plurality of user ordered programming for multiplexed transmission over a conventional cable TV system from a video library source to a user's residence, and at each of the plurality of physical locations to which the programming is delivered is located a device to permit the intelligent viewing of only programs so ordered from that location. Both fail to consider the problem of migrating receiving apparatus. This is a serious concern as a descrambler located at a user's private residence which is authorized to receive a boxing match, for example, may be relocated for use to a public establishment where viewing of the match is not authorized. Both propose the use of the public telephone network as the ordering link between the subscriber's residence and the library. The use of both the public telephone network and a conventional CATV distribution system represent potential blocking problems. Congestion can appear in both the ordering path and the delivery path.
(Non Blocking Need) Another object of this invention is to design a delivery path that is expandable on an as required basis to ensure that as the demand for programming grows the system is capable of being modified to meet the demand.
(Copy Protection) A concern of programming copyright owners is that electronically delivered programming once received can be recorded and copied for unauthorized distribution. Present art discourages recording by altering the nature of the video signal such that subsequent recording is interfered with. Users who wish to make a business out of such a practice use video signal restoration apparatus to restore the video signal to a recordable form thus defeating the copy security system. Another object of this invention is a system of imbedding in the video signal information that allows the user responsible for the unauthorized distribution practice to be determined.
(Payment Responsibility) Another object of this invention is apparatus for securely enabling the purchasing of programming and/or consumer goods. The implementation of such a feature requires that the physical location of the user be correctly identified and is free from tampering, and that the personal identification of the ordering user be identified and valid for the ordering address. The purpose being to minimize problems associated with users denying responsibility for payment.